(1) Field of the Invention
The present invention relates in general to an automotive air conditioning system and, more particularly, to a heater unit of the system which has a demisting or defrosting duct from which warm air is discharged toward front and side windows of the vehicle to demist or defrost the same.
(2) Description of the Prior Art
In order to demist or defrost the front and side windows of a vehicle, a heater unit of an automotive air conditioning system is provided with a demisting or defrosting duct mounted near the windows. Upon the requirement for demisting, for example, a valve means associated with the duct is manipulated to open, thereby discharging warm air therefrom toward the windows to demist the same. Usually, the air flow toward both the front and side windows is controlled by a common flap valve. However, in this case, it is impossible to control air flows directed toward the front window and side windows independently. Thus, precise demisting or defrosting operation to each window is not expected from such arrangement. Two conventional heater units are described hereinafter, to clarify the task of the present invention.